Here's an idea of how to get into comics without continuity- graphic novels and alternate storyline tales. They're usually self-contained beginning to end stories that don't need much other than general knowledge of a hero and his universe. Seen any of the new Batman movies, the Tim Burton movies, or Batman: The Animated Series and it's movies? Congratulations, you now know enough to read and understand The Dark Knight Returns, Batman: Long Halloween, Batman: Arkham Asylum (Not related to the game, though similar), and plenty more. Or, hell, you could pick up one-off graphic novels that are completely self-contained universes, like Watchmen. Unfortunately, if you're a Marvel fan, there aren't as many as those as there are for DC, but like Bob said, you could always get a trade.
Note: Seriously, Escapist? An "é" in my capture? Maybe you should get a different Captcha provider. These don't seem to be the best Captchas I've had to deal with.